refactor(main): finish TASK-94 composition-root extraction

Move IPC, shortcuts, startup lifecycle, and app-ready assembly behind dedicated runtime composers so main.ts stays focused on boot wiring while preserving behavior and test coverage.

src/main/runtime/composers/ipc-runtime-composer.ts

@@ -0,0 +1,75 @@
+import type { RegisterIpcRuntimeServicesParams } from '../../ipc-runtime';
+import {
+  createBuildMpvCommandFromIpcRuntimeMainDepsHandler,
+  createIpcRuntimeHandlers,
+} from '../domains/ipc';
+
+type MpvCommand = (string | number)[];
+
+type IpcMainDepsWithoutHandlers = Omit<
+  RegisterIpcRuntimeServicesParams['mainDeps'],
+  'handleMpvCommand' | 'runSubsyncManual'
+>;
+
+type IpcRuntimeDeps<TRequest, TResult> = Parameters<
+  typeof createIpcRuntimeHandlers<TRequest, TResult>
+>[0];
+
+export type IpcRuntimeComposerOptions<TRequest, TResult> = {
+  mpvCommandMainDeps: Parameters<typeof createBuildMpvCommandFromIpcRuntimeMainDepsHandler>[0];
+  handleMpvCommandFromIpcRuntime: IpcRuntimeDeps<
+    TRequest,
+    TResult
+  >['handleMpvCommandFromIpcDeps']['handleMpvCommandFromIpcRuntime'];
+  runSubsyncManualFromIpc: (request: TRequest) => Promise<TResult>;
+  registration: {
+    runtimeOptions: RegisterIpcRuntimeServicesParams['runtimeOptions'];
+    mainDeps: IpcMainDepsWithoutHandlers;
+    ankiJimakuDeps: RegisterIpcRuntimeServicesParams['ankiJimakuDeps'];
+    registerIpcRuntimeServices: (params: RegisterIpcRuntimeServicesParams) => void;
+  };
+};
+
+export type IpcRuntimeComposerResult<TRequest, TResult> = {
+  handleMpvCommandFromIpc: (command: MpvCommand) => void;
+  runSubsyncManualFromIpc: (request: TRequest) => Promise<TResult>;
+  registerIpcRuntimeHandlers: () => void;
+};
+
+export function composeIpcRuntimeHandlers<TRequest, TResult>(
+  options: IpcRuntimeComposerOptions<TRequest, TResult>,
+): IpcRuntimeComposerResult<TRequest, TResult> {
+  const mpvCommandFromIpcRuntimeMainDeps = createBuildMpvCommandFromIpcRuntimeMainDepsHandler(
+    options.mpvCommandMainDeps,
+  )();
+  const { handleMpvCommandFromIpc, runSubsyncManualFromIpc } = createIpcRuntimeHandlers<
+    TRequest,
+    TResult
+  >({
+    handleMpvCommandFromIpcDeps: {
+      handleMpvCommandFromIpcRuntime: options.handleMpvCommandFromIpcRuntime,
+      buildMpvCommandDeps: () => mpvCommandFromIpcRuntimeMainDeps,
+    },
+    runSubsyncManualFromIpcDeps: {
+      runManualFromIpc: (request) => options.runSubsyncManualFromIpc(request),
+    },
+  });
+
+  const registerIpcRuntimeHandlers = (): void => {
+    options.registration.registerIpcRuntimeServices({
+      runtimeOptions: options.registration.runtimeOptions,
+      mainDeps: {
+        ...options.registration.mainDeps,
+        handleMpvCommand: (command) => handleMpvCommandFromIpc(command),
+        runSubsyncManual: (request) => runSubsyncManualFromIpc(request as TRequest),
+      },
+      ankiJimakuDeps: options.registration.ankiJimakuDeps,
+    });
+  };
+
+  return {
+    handleMpvCommandFromIpc: (command) => handleMpvCommandFromIpc(command),
+    runSubsyncManualFromIpc: (request) => runSubsyncManualFromIpc(request),
+    registerIpcRuntimeHandlers,
+  };
+}